1. Field of the Invention
The invention relates to a ring oscillator. More particularly, the invention relates to an inverting delay unit of a ring oscillator.
2. Description of Related Art
A ring oscillator is commonly applied to generate periodic clock signals due to its simple circuit structure. According to the related art, the ring oscillator can be composed of a plurality of inverters serially connected in a form of a ring. Conventionally, the number of stages of inverters is often increased or decreased, or dimensions of transistors in the inverters are adjusted, so as to control the frequency of the clock signals which are generated by the ring oscillator. Namely, in order to generate the clock signals with the reduced frequency, the number of stages of inverters in the conventional ring oscillator need be effectively increased, and/or the transistors in the inverters need be enlarged.
Note that signals transmitted between the inverters in the ring oscillator are continuously transited. During signal transition, the transistors of the inverters serially connected between power sources are simultaneously turned on, which results in current leakage. The increase in the number of stages of the inverters and/or the increase in the dimensions of transistors in the inverters will further result in significant current leakage. Moreover, the clock signals generated by the conventional ring oscillator may jitter to a great extent, thus posing a negative impact on the signal quality.